Showing papers by "Daido University published in 2021"

Ammonia Formation Catalyzed by a Dinitrogen-Bridged Dirhenium Complex Bearing PNP-Pincer Ligands under Mild Reaction Conditions**

Abstract: A series of rhenium complexes bearing a pyridine-based PNP-type pincer ligand are synthesized from rhenium phosphine complexes as precursors. A dinitrogen-bridged dirhenium complex bearing the PNP-type pincer ligands catalytically converts dinitrogen into ammonia during the reaction with KC8 as a reductant and [HPCy3 ]BArF 4 (Cy=cyclohexyl, ArF =3,5-(CF3 )2 C6 H3 ) as a proton source at -78 °C to afford 8.4 equiv of ammonia based on the rhenium atom of the catalyst. The rhenium-dinitrogen complex also catalyzes silylation of dinitrogen in the reaction with KC8 as a reductant and Me3 SiCl as a silylating reagent under ambient reaction conditions to afford 11.7 equiv of tris(trimethylsilyl)amine based on the rhenium atom of the catalyst. These results demonstrate the first successful example of catalytic nitrogen fixation under mild reaction conditions using rhenium-dinitrogen complexes as catalysts.

Influence of a plasma-treated nutrient solution containing 2,4-dichlorobenzoic acid on the growth of cucumber in a hydroponic system

Abstract: Allelochemicals are organic compounds exuded from the roots of plants, which have autotoxic effects on plant growth. In this study, the decomposition of 2,4-dichlorobenzoic acid (DCBA), an allelochemical of cucumber, by plasma generated in an air bubble in solution is examined, and the influence of plasma treatment of the solution on cucumber growth in a hydroponics system is investigated. Air gas is injected into water through a vertically positioned glass tube, into which a high-voltage wire electrode is placed to generate plasma. The concentration of DCBA decreases and the concentration of chloride ion produced by the dichlorination of DCBA increases with increasing discharge treatment time. Consequently, most DCBA has decomposed after 24 h of treatment. The discharge-treated solution is used as a nutrient solution for cultivating cucumber plants in a rockwool hydroponic system. The results show that the growth of most plants is inhibited by adding DCBA, as well as by the decrease in pH during discharge treatment; in contrast, plants subjected to discharge treatment with pH adjustment grow healthily.

Finite Element-Based Analysis of Bio-Heat Transfer in Human Skin Burns and Afterwards

Abstract: This research was conducted to develop the three-dimensional (3D) finite element model of human skin for bio-heat transfer analysis. The skin burn was analyzed using Penne’s bio-heat equation, whic...

Effect of Oxidation on Surface Properties of AISI H13 Tool Steel Nitrided by Atmospheric-Pressure Plasma

Abstract: Plasma nitriding is widely used for treating various engineering materials to achieve increased surface hardness while maintaining the core properties of the material. Nitridation increases the wear, fatigue, and corrosion resistance, as well as the surface hardness, of a material. At present, glow discharge plasma nitriding is the most common plasma nitriding method;1–5) however, this requires a vacuum system to generate plasma. Therefore, most traditional plasma nitriding methods can only be performed as a batch process, leading to a high cost of capital.6) For this reason, we are developing a new plasma nitriding method that is conducted under atmospheric pressure, as previously reported.7) One of the biggest problems with plasma nitriding under atmospheric pressure is oxidation. Due to the high treatment temperature of the sample, oxidation occurs from the oxygen in the air. In conventional plasma nitriding, the sample is not oxidized because the process is conducted in a vacuum. In samples that form an oxidized film, nitrogen is not diffused into the sample;8,9) therefore, preventing oxygen from getting into the treatment zone is crucial.10) The conventional DC glow discharge plasma method enables surface hardening to remove Effect of Oxidation on Surface Properties of AISI H13 Tool Steel Nitrided by Atmospheric-Pressure Plasma

A Relation of Preconditioners in Domain Decomposition Method for Magnetostatic Problems

Abstract: An iterative domain decomposition method is proposed for numerical analysis of 3-dimensional (3D) linear magnetostatic problems taking the magnetic vector potential as an unknown function. The iter...

Reducing pressure oscillation in high-load HCCI combustion via air injection before compression:

Abstract: Pressure oscillation often occurs in high-load homogeneous charge compression ignition (HCCI) combustion, which is a challenge in the development of HCCI engines for automobiles. This work proposes...

Accurate estimation of workpiece dimension in plunge grinding without sizing gauge

Abstract: In the cylindrical grinding process, the residual grinding allowance is left owing to the rubbing of the abrasive grains and the elastic deformation of the grinding system caused by the large normal grinding force. Therefore, a sizing gauge is generally used to monitor the workpiece diameter during the process. However, the sizing gauge disturbs the grinding operations, such as loading and unloading the workpiece. In this study, a new method for estimating the grinding stock of a ground workpiece is proposed. In the proposed method, the grinding stock can be estimated without a sizing gauge. The removed volume of the workpiece can be calculated from the power consumption of the wheel motor, which is easily measured. Before the grinding experiments, the specific grinding energy is determined from several grinding results. During the grinding process, the grinding stock of the ground workpiece was estimated using the determined specific grinding energy. It was confirmed that the grinding stock could be accurately estimated under several grinding conditions.

Calibration and Validation of Stress–Strain Curve in High-Strain Region of Mild Steel Sheet

Abstract: Stress–strain curve in the high-strain region is one of the most important models that must be taken into consideration for high-precision sheet metal forming simulation. In this study, using mild steel sheets, tensile tests were conducted with a necked shape specimen at the center in order to generate non-uniform elongation. Using image analysis, strain–load relationships were obtained using multiple gauge lengths, and stress–strain relationships were obtained by inverse analysis using FE simulation. With a sufficiently small gauge length it is possible to get stress–strain curve in the high-strain region. The advantage of this method is that the experiments can be implemented only with a uniaxial tensile test. For validation, the original hole expansion test model that is not affected by friction is proposed. The thickness strain distribution along the hole with large plastic strain is compared with the experimental and numerical results to indicate the validity of this method.

Text-Dependent Closed-Set Two-Speaker Recognition of a Key Phrase Uttered Synchronously by Two Persons

Abstract: In this paper, we propose a novel text-dependent speaker recognition system using a key phrase uttered synchronously by two persons, ie, uttered in unison Hereafter, we refer to this speech as a duo utterance This proposed system accepts the duo utterance uttered by the enrollment speaker pair but rejects the duo utterance from other speaker pairs and the utterance uttered by a single speaker The difference from the conventional speaker recognition systems is that the proposed system requires the duo utterance for speaker recognition Hence, it is expected that the proposed system is a high-level security system because this system requires duo utterance To realize this proposed system, we have employed a d-vector and a hidden Markov model (HMM) The d-vector is the feature vector extracted by a speaker identification deep neural network (DNN) that is trained to identify the speakers and the speaker pairs using the frame-level acoustic features Additionally, it is widely known that the HMM is suitable for the speaker model of text-dependent speaker recognition system To evaluate the proposed method, we conducted speaker identification experiments Experimental results show that the proposed system achieved higher performance than the MFCC-based system In addition, we investigated the errors of the experimental results for improving future systems

Hydro-Mechanical Deep Drawing of Locally Solution-Treated Aluminum Alloy Sheets

Abstract: Improvement of formability of aluminum alloy sheets is desired because of their lower drawability than mild steel. Therefore, the special sheet forming methods such as a hydro-mechanical forming and a tailor heat treated blank have been developed for aluminum alloy sheets. In this study, we combined both the methods and investigated the limit of drawing ratio of tailor heat treated blanks in a hydro-mechanical forming process. Tailor heat treated blanks of A6061-T6 sheets were produced by the local solution treatment which was conducted by heat transfer from metal plates heated to a high temperature. Hydro-mechanical deep drawing tests were performed using a cylindrical punch. The limit of drawing ratio of tailor heat treated blanks in a hydro-mechanical forming process was higher than that of simple hydro-mechanical forming and that of simple tailor heat treated blanks.

Effects of graded porous structures on the mechanical and electrical properties of Ketjenblack/silicone-rubber composites

Abstract: In this study, Ketjenblack/silicone-rubber composites with gradually changing pore sizes are produced to develop strain sensor materials whose electrical resistivities change with an increase in strain. The pore sizes and distributions are evaluated by X-ray computed tomography and compared to uniform porous composites containing the same ingredients. Results showed that the resistivities of the graded porous composites decreased more significantly than those of the uniform porous composites at high compression rates of greater than 20%. Analytical results of strain distribution based on the digital image correlation method indicated that the resistivity changes at high compression rates were caused by a gradual increase in size of the area with low resistivity. The changes in resistivity demonstrated that graded porous composites are promising strain sensor materials that can be used under high compression rates.

Judging Emotion from EEGs Using Pseudo Data

Abstract: For a robot to converse naturally with a human, it must be able to accurately gauge the emotional state of the person. Techniques for estimating the emotions of a person from facial expressions, intonation and speech content have been proposed. This chapter presents a technique for judging the emotion of a person from EEGs by SVM using pseudo extended data. The accuracy of emotion judgment from EEG features using at random pseudo extended data was 25.0% and using proposed extension technique was 30.0%. However, performance accuracy remains low, and continued development is required through further development of methods for both reducing noise mixed with EEGs.

Boundary limits of monotone Sobolev functions on metric spaces

Abstract: In this paper we are concerned with weighted boundary limits of monotone Sobolev functions in Orlicz spaces on bounded $(\eta,\psi)$-John domains in a metric space. We also deal with Lindelof type theorems for monotone Sobolev functions on uniform domains in a metric space.

Generic Object Recognition Using Both Illustration Images and Real-Object Images by CNN

Abstract: In recent years, the development of robots has been carried out for making human life more convenient and more comfortable along with the development of artificial intelligence. It is necessary for the robot to recognize the surrounding environment. However, in the surrounding environment there are objects other than real objects such as illustrations and paintings. When recognizing an image showing an illustration image with the current object recognition system which learned using real-object images, the recognition rate is very low (about 65%). In this research, we aim to recognize both illustration images and real-object images, and we verified whether the pseudo illustrated image which processed contour processing and the color reduction processing to the real image is effective for the recognition of the illustrated image.